Electronics converting sine waves to current

[Amy54]

How are sine waves converted to current??
Im doing avionics in physics at the moment and we are talking about receivers... i now that the resonate oscilates at certain frequency and the antenna picks up the sine waves that are at the frequency... but how are they then turned into current??
thanks! :)

 

[dst]

They get cosined


No really, "sine waves" are a mathematical tool, not real waves! What you're thinking about are photons/electromagnetic waves.

It's an outcome of Maxwell's equations, if I remember correctly. An alternating current in an antenna causes electrons to move back and forth. According to Maxwell, if a moving charge decreases in velocity then it has to emit energy (in the form of photons). These photons carry a specific amount of energy and the reciever picks specifically these up.

If I remember correctly, the reciever also picks up all sorts of crap which is where a ****load of techniques (both mathematical and physical) to isolate the one signal.

Another "if I remember correctly", the antenna has to be a certain length or some other to induce a standing wave in the antenna.

 

[Paulanddiw]

It's done with a type of recifier (in receivers is called the detector)